I remind myself almost daily that fake news is not new. Think of the days of William Randolph Hearst and yellow journalism. Think of all the times you’ve been on the checkout line at the grocery store and read those headlines about the woman who married a three-headed alien. But for some reason, it especially upsets me every time I read science headlines and “news stories” that are nothing more than sensationalist nonsense. I guess it’s that I feel that science is our search for truth…and it’s also a means of alleviating so much suffering.
Well, this week, it was Forbes that has me all riled up: “No Scientific Evidence That Probiotics Improve Anxiety Symptoms In Humans, Finds Study.”[i] The truth is, that’s really not at all what the paper in question found. But I guess “A lot more scientific evidence is needed before we know how to treat anxiety with probiotics because the studies published so far have been wholly inadequate” doesn’t have the same ring to it.
First, a summary of the actual article[ii]: it is a review of 36 studies done on rodents and humans and covers a variety of probiotic strains. The authors were looking for evidence in the literature that probiotics can positively affect the symptoms of anxiety. According to Forbes, “…it turned up zero evidence that humans with self-reported anxiety symptoms benefited from taking any of them.” There was some efficacy in diseased rodents using the strain L. rhamnosus.
Now let’s look at what this article is really telling us:
Ironically, Forbes actually quotes the lead author of the study, “We’re not saying they do nothing, but we have a lot to figure out before we know if they can be used therapeutically.” That’s pretty darn different from “no scientific evidence.
If you read to the bottom of the Forbes article, which most people don’t do, you’ll find that the lead author points out that one reason there may have been some efficacy in rodents versus humans is that there is a huge disparity in the relative doses used in animal versus people: “If you control for the weights of animals versus humans, animals are getting much larger doses of probiotics in these experiments by one or two orders of magnitude. Sometimes the doses were hundreds of times higher than we see in human studies…”
So perhaps the human studies fail to show efficacy simply because people are taking way too small a dose. VSL#3 is by far the most clinically studied probiotic on the market today. Taking a look at just 1 study[iii] on VSL#3, this one in ulcerative colitis, you’ll notice that to achieve efficacy, the patients took 1.2 TRILLION organisms per day. To give you some idea of comparison, here’s just one example: one of the studies that did make into this meta-analysis studied people with IBD. The “high dose” group was given 30 billion organisms per day.
Forbes actually acknowledges that it’s important to note that the authors “… were clear that the anxiety levels among the human participants in the reviewed studies weren’t necessarily ‘clinically elevated.’” Wait so…the people who didn’t get relief from anxiety didn’t actually have anxiety disorders?! You read that correctly. From the paper itself: “Eight studies assessed the effect of probiotic administration on healthy samples, while six studies did so with clinical samples. Of the six studies that used clinical participants, four studies investigated participants with irritable bowel syndrome, one study investigated participants with at least moderate mood disturbance, and one study investigated participants with cancer.”
But wait, there’s more. If you read the actual paper, and take Forbes’ reporting out of the equation, you find some pretty interesting things. Here are just a couple:
1. RE: the animal studies:
For reasons not explained, the authors excluded papers in which the probiotic was not living at the time of administration, meaning that any study that used heat-killed organisms was excluded. That would mean then, as just a quick example, that the two studies done by Dr. Christopher Lowry’s group at the University of Colorado-Boulder, which I wrote about a couple of weeks ago (in which mice were inoculated against anxiety using a heat-killed strain of probiotic) were not used.
2. RE: the human studies
There were many issues with the studies included, according to the paper’s authors themselves, including the fact that the measure of anxiety was self-reported, which is entirely subjective. (MRI imaging, for example, would have provided more objective results). Secondly, only half the papers included had probiotics administered for at least 8 weeks. Thirdly, they also point out that there was a huge level of heterogeneity among the human studies, with variability in the doses, the lengths of treatment, the kinds of probiotics used (multi-strain versus single strain, for example), etc.
So while Forbes’ headline categorically states that the study found no scientific evidence that probiotics can improve anxiety in humans, the papers’ authors state flat out that “…appropriate caution still needs to be taken when interpreting the present results, as they may not accurately reflect the true effect of probiotics.”
I am not a scientist yet it was easy for me to see many flaws in both the actual paper (which the authors did acknowledge right in the paper) and in Forbes’ coverage of it.
Anyone else tired of reading pathetic reporting? Is it really so hard to cover a story with some degree of objectivity and scientific veracity?
[ii] Reis, DJ, Ilaardi, SS, Punt, SEW. The anxiolytic effects of probiotics: A systematic review and met-analysis of the clinical and pre-clinical literature. PLoS One. 2018: https://doi.org/10.1371/journal.pone.0199041
[iii] Bibiloni, R, Fedorak, RN, Tannock, GW, Madsen, KL, Gionchetti, P, Campieri, M, De Simone, C, Sartor, RB. VSL#3 probiotic-misture induces remission in patients with active ulcertavie colitis. American Journal of Gastroenterology. 2005:100(7):1539-46.